Thanks for all the input guys!

Jmac: Excellent information - Thanks very much! I've tried similar methods to the one you presented. Your method produced the same length and slightly larger diameter than the method I've used previously.

Datto1000wagon: They look like a decent set of headers. They are the shortest shortest primary length I've seen on any 4-1's for a Datsun.

My gut feeling is the same as yours, Benny & 1000coupe. 4-1's are for the track and 4-2-1's are for the street. Thats the main reason why I'm kinda snobbing the JTS units at the moment, despite all the good reports they get on this website.

Got a price from the manufacturer, 'Liverpool Exhausts' for the hurricane 4-1's. They are $250 direct plus postage (which sounds really cheap to me). He's going to give me the diameters and lengths tomorrow. I'll post them up when I get them. Oh, and the Hurricane headers are Mandrel bent, unlike the Hi-tec's.

Also, just to clear the air for others, the parts Stewart Wilkins Motorsport sell are the JTS items.

you could always look into Coby extractors from Coby Manufacturing in Hamilton, NZ. I use them and they look good, although how they fare in terms of ultimate performance I'm not sure. Also unsure whether they would fit the 1000 but they would probably be able to tell you. The model you would want is the twin carb model, it doesn't fit when using the standard inlet manifold. I could probably give you some measurements ie tube dia. and approx length if needed. I would say looking at them they would be approximately tuned length but not exactly.

Also they are 4 into 1

Daniel,make sure you guys do a trial fit before parting with any dough,i still think they'll foul on the idler arm.
Cheers

I will have a look at a set I have tomorrow because I know they foul the idler arm in my kb10.

What they actually foul on is the grease nipple on the idler arm, so fingers crossed if I take the nipple out and plug it with something it might work. l'll let you know when I know.

Cheers

I went down the road of very long primaries (1.5" x 28") baffle collectors then short secondaries (1.75" x 12") then a merge collector to a 2" diam. tailpipe.

Info for these dimensions is from "Four Stroke Perormance Tuning" by A Graham Bell.

These pipes perform like 4 into 1`s but with more midrange.

Cost only $280 in 316 stainless mandrel bends and tube. but about 30 hours of work!

A15, 271deg cam, hi comp, 500mm intake runners and injected.

Quote:


Thats a killer book, Full of relitivly easy to absorbe information!?

That book is a great read, I have a copy myself aswell. Its covers most things on car preparation for street and track. I have read it and re-read it many times.

It has a whole chapter covering exhaust systems.

Not a fan of cobys at all. Atleast the ones for a series. Always fouled the idler arm, and never seemed to line up with anything.
Might be different now but I really don't want to have to deal witht them again, weather they're the D1 or D2 style ones.

Really good information here, keep it going.

Hi fellas, I am about to build a set of extractors for my rig as the old ones are really rusty and a new set of painted steel ones from the exhaust shop here cost $330!
I want to build these ones out of stainless. no more rust!

I was planning on building an equal length 4 > 2 > 1 as I am of the impression that they utilise the effect of the negative/low pressure created after each exhaust pulse passing through the pipes?

For those that arent familiar with this concept I drew a basic diagram of how I understand this effect to work, but If I am wrong then please correct me:




Red path is positive exhaust pressure pulse travelling down pipe.

Blue path is negative (or low) pressure created from the passing of the high pressure exhaust pulse.

Using this design the negative/low pressure pulse "pulls" the next pipe's positive pulse through the first Y collecter.

Then each pair of Y's collects again and the effect is repeated through the 3rd Y, thus 'pulling' through each of the first Y's.

Is this correct?
I was of the impression that this makes the Tri Y design more effecient.

maybe you can shed some light Jmac?